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    <!--

    @license twgl.js Copyright (c) 2015, Gregg Tavares All Rights Reserved.
    Available via the MIT license.
    see: http://github.com/greggman/twgl.js for details

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    <title>twgl.js - tiny</title>
    <style>
      body {
          margin: 0;
          font-family: monospace;
      }
      canvas {
          display: block;
          width: 100vw;
          height: 100vh;
      }
      #b {
        position: absolute;
        top: 10px;
        width: 100%;
        text-align: center;
        z-index: 2;
      }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
    <div id="b"><a href="http://twgljs.org">twgl.js</a> - tiny</div>
  </body>
  <script id="vs" type="notjs">
attribute vec4 position;

void main() {
  gl_Position = position;
}
  </script>
  <script id="fs" type="notjs">
precision mediump float;

uniform vec2 resolution;
uniform float time;

void main() {
  vec2 uv = gl_FragCoord.xy / resolution;
  float color = 0.0;
  // lifted from glslsandbox.com
  color += sin( uv.x * cos( time / 3.0 ) * 60.0 ) + cos( uv.y * cos( time / 2.80 ) * 10.0 );
  color += sin( uv.y * sin( time / 2.0 ) * 40.0 ) + cos( uv.x * sin( time / 1.70 ) * 40.0 );
  color += sin( uv.x * sin( time / 1.0 ) * 10.0 ) + sin( uv.y * sin( time / 3.50 ) * 80.0 );
  color *= sin( time / 10.0 ) * 0.5;

  gl_FragColor = vec4( vec3( color * 0.5, sin( color + time / 2.5 ) * 0.75, color ), 1.0 );
}
  </script>
  <script type="module">
    import * as twgl from '../dist/4.x/twgl-full.module.js';
    const gl = document.querySelector("#c").getContext("webgl");
    const programInfo = twgl.createProgramInfo(gl, ["vs", "fs"]);

    const arrays = {
      position: [-1, -1, 0, 1, -1, 0, -1, 1, 0, -1, 1, 0, 1, -1, 0, 1, 1, 0],
    };
    const bufferInfo = twgl.createBufferInfoFromArrays(gl, arrays);

    function render(time) {
      twgl.resizeCanvasToDisplaySize(gl.canvas);
      gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

      const uniforms = {
        time: time * 0.001,
        resolution: [gl.canvas.width, gl.canvas.height],
      };

      gl.useProgram(programInfo.program);
      twgl.setBuffersAndAttributes(gl, programInfo, bufferInfo);
      twgl.setUniforms(programInfo, uniforms);
      twgl.drawBufferInfo(gl, bufferInfo);

      requestAnimationFrame(render);
    }
    requestAnimationFrame(render);
  </script>
</html>


